• A Hard-Wired Data Acquisition Device for Neurophysiology

      Kuhl, Frederick S.; Walter Reed Army Institute of Research (International Foundation for Telemetering, 1975-10)
      Neurophysiologic experiments are becoming increasingly numerical in nature, and may result in large quantities of data which may be practicably analyzed only by computer. A non-programmable digital controller was constructed to acquire data from a variety of remote neurophysiology experiments and to store them on magnetic tape for transport to an off-line computer. The advantages of the unit's modular design are illustrated.
    • Runs of Significant Samples for Processes with Sharp Non-Stationarities: Application to Seismogram Compression

      Babkin, V. F.; Rybeva, N. E.; Shtarkov, Yu. M.; Institute for Space Research (International Foundation for Telemetering, 1975-10)
      An algorithm for threshold compression of the processes with the sharp variations of a level is considered. In broadening the concept on an significant sample we are successful in transmitting completely almost all the samples appropriate to the phenomenon studied; at the same time the compression ratio at the quiet parts is kept at the acceptable level. The experimental results of seismogram compression are given.
    • Intersatellite (Nd:YAG) Laser Communications; A System For The 1980's

      Barry, J. D.; Wright-Patterson AFB (International Foundation for Telemetering, 1975-10)
      It is now a certainty that laser communication systems will be operating in space within this decade. The development of a laser communications satellite package began this fall and is to be launched in 1979. The system is to operate at 1000 megabits per second. Laser communications technology has proceeded from purely exploratory research just over five years ago to the successful completion and operation this year of an engineering feasibility model of the satellite system. Laboratory tests have verified the system capability at a serial data rate of 1000 megabits per second. Thermal and vibrational tests have been successfully completed to the test levels of the Defense Meteorological Satellite program.
    • A Distributed Computing Approach to Mission Operations Support

      Larsen, Ronald L.; NASA's Goddard Space Flight Center (International Foundation for Telemetering, 1975-10)
      The ever-evolving nature of spacecraft Support operations requires computing systems which can adapt to dynamic support requirements. These systems must exhibit a high degree of reliability, perform a wide spectrum of services, and be able to grow incrementally in response to demand. A distributed computing network is proposed as a system architecture displaying the desired attributes. The proposed system employs functional specialization of resources, featuring high performance scientific processing, real-time response, and interactive operations. Fundamental to the approach is the notion of process-to-process communication, which is effected through a high-bandwidth communications network. Both resource-sharing and load-sharing may be realized in the proposed system.
    • The Mars Penetrator Telemetry and Control System

      Bentley, R. D.; Campbell, A. B.; Sandia Laboratories (International Foundation for Telemetering, 1975-10)
      A new method for exploring the planet Mars has been proposed* that will use ground-penetrating vehicles to carry scientific instruments below the Martian surface. The subsurface performance of various sequences of complicated experiments poses challenges in the design of the telemetry and control links. This article describes the overall mission, the penetrator, the constraints imposed by the mission and the penetrator, and a design for the telemetry/control system. This design uses a microprogrammed microprocessor; the sequences of commands are stored in a Read-Only-Memory (ROM), and a particular sequence is initiated by transmitting from the Earth the address in the ROM that contains the first of the commands for the specific sequence to be performed. Data from the experiments are stored in a memory for later transmission to an orbiter that serves as a relay station for the command and data links with Earth.
    • The Common Element Approach to Telemetry Processing Systems

      Karleskint, Daniel J.; Control Data Corporation (International Foundation for Telemetering, 1975-10)
      This paper postulates a complete computerized telemetry processing system which has only one basic hardware module as the system building block. A discussion of the technology incorporated in the system and its effect on systems cost and complexity is included.
    • Charge Coupled Device (CCD) Analog Signal Processing

      White, Marvin H.; Westinghouse Defense & Electronic Systems Center (International Foundation for Telemetering, 1975-10)
      A discussion of the CCD basic building blocks for analog signal processing with particular emphasis on application for telemetry. Serial in/Serial out (SI/SO) blocks provide time base translation electrically alterable delay, and sequential TDM filters, Parallel In/Serial Out blocks are useful in time divisions multiplexing (TDM) and Serial In/Parallel Out blocks for variable tapped delay lines, filters and correlators. Combinations of the above linear or one-dimensional blocks provides two-dimensional arrays for filter banks, multiple correlators, etc. Particular telemetry applications are FM filters, Parallel Correlators, Matched Filters, Single Sideband Modulators and Adaptive line equalizers.
    • Real Time Data Compression for Rae-B Spacecraft Camera

      Miller, W. H.; NASA-Goddard Space Flight Center (International Foundation for Telemetering, 1975-10)
      A real time data compression unit was designed and fabricated for the Radio Astronomv Explorer Lunar Mission Antenna Aspect Camera. The camera takes a panoramic view of spacecraft, moon, etc. of ±35 degrees by 360 degrees. This data compressor combined information reduction and redundancy reduction. The information reduction was accomplished by subsampling (used every fourth line): and the redundancy reduction was accomplished by an adaptive run-length encoder. The adaptive run-length encoder used a zero-order predictor. Two different maximum run-lengths were used with two different data formats. Selection of the operating format depended on the sampled gray level compared to a fixed threshold. Statistical data and images indicate that the redundancy reduction technique yields a compression ratio of 8:1. Thus a combined compression ratio of 32:1 was obtained on an entire panoramic view.
    • A Fixed Sampling Rate Vocoplexer

      Lerner, Theodore; Textron Bell Aerospace (International Foundation for Telemetering, 1975-10)
      The vocoplexer is a system which permits a reduction in the data rate required to transmit voice signals when many such signals are multiplexed onto a common digital line. This is accomplished through the use of a coding technique which is based on the statistical properties of voice signals. The reduction in data rate that can be realized by the vocoplexer is a function of the speech quality required. Typically, for a speech quality equivalent to PCM at 8,000 samples per second and five bits per sample, a reduction in data rate to about 1/3 can be accomplished. The descriptions in this paper are based on this quality requirement. However, for a somewhat reduced quality requirement, even greater savings can be accomplished. For example, if quality equivalent to PCM at 8,000 samples per second at four bits per sample is adequate, the vocoplexer will require approximately 9,600 bits per second. For quality equivalent to delta modulation at 18,000 bits per second the vocoplexer requires approximately 6,400 bits per second per voice channel.
    • The Automatic Analysis of Aerial Photographic Data

      Chen, C. H.; Southeastern Mass. Univ. (International Foundation for Telemetering, 1975-10)
      As the volume of aerial photographic data increases in various applications, there is increasing demand for automated data analysis. Faster and larger computer alone is not the solution. In this paper effective and computationally efficient techniques for computer processing of the aerial photographic data are presented. They include: (1) picture data compression, (2) feature exttraction using the histograms of the original and sharpened pictures, (3) sequential target and classification, (4) threshold selection, and (5) Walsh power spectrum analysis. All of these techniques may be incorporated in a fully automated data analysis system to meet certain real-time on-line system requirement.
    • An Analog Memory Device

      Uzunoglu, Vasil; COMSAT Laboratories (International Foundation for Telemetering, 1975-10)
      The analog memory device is a combination of a bipolar and a MOSFET device which stores information in analog form for several hours or more with no degradation of data. The emitter base junction of a bipolar transistor is covered with an SiO₂ layer and a voltage is applied to this point. With zero volts applied, the unit acts as a bipolar transistor. Increasing the voltage at this point increases the emitter injection efficiency of the bipolar transistor, which in turn increases the current gain of the device. An SiO₂ layer with no leakage paths can retain the charge applied to it for long periods of time; thus the gain will remain at this level as long as the charge remains on the oxide layer. A large number of such devices can be fabricated on a single chip. Such devices combined with other integrated circuits can be used, for example, for automatic equalization of transmission lines, echo suppression, and correlation detection.
    • Multibeam Adaptive Array for RPV Antijam Communication

      Noji, T. T.; Schwartz, L.; AIL (International Foundation for Telemetering, 1975-10)
      An application using a multibeam adaptive array for the simultaneous communications of command control, and telemetry data from 20 Remotely Piloted Vehicles (RPV's) to a command station is investigated. It is assumed that the RPV's are on tactical mission beyond FEBA as typically shown in Figure 1, and that communication links must be established to and from each RPV in the presence of many airborne and/or surface based jammers. The RPV's are assumed to be on data collection missions out to a maximum range of 100 km and must data link the sensor information (including digitized video of 20 Mbps) back to the tactical RPV control center. The data link will be operated at C-band. Other system parameters are summarized in Figure 2.
    • Digital Clock Recovery Scheme Masks Tape Errors

      Welch, James P.; Odetics, Inc. (International Foundation for Telemetering, 1975-10)
      The bit error rate (BER) of the tape recorder is a primary factor in determining the overall accuracy of a space to ground PCM data link. The ultimate goal is to obtain a recorder BER signature that is dependent solely on tape quality; however, in practice, the BER may be several orders of magnitude worse than the goal. Usually this occurs when the data transfer rate is not preserved during dropout intervals - intervals where the net signal-to-noise ratio is insufficient to guarantee valid data cell boundary detection. This paper investigates tape dropout signatures and addresses the problem of maintaining time coherency between reproduced data and clock assurance throughout the dropout interval. A digital approach is presented that utilizes a dual threshold detector in conjunction with a clock recovery generator. The generator is synchronized to the tape signal by a clock, N-times the data transfer rate, coherent with the transport servo reference. Implementation of the approach is discussed for two popular PCM formats. The effectiveness of the approach as a function of cell boundary detection, system signal-to-noise ratio, and transport time base error (TBE) is considered.
    • Performance of Coded MFSK in a Rician Fading Channel

      Modestino, J. W.; Mui, S. Y.; R.P.I. (International Foundation for Telemetering, 1975-10)
      The performance of convolutional codes in conjunction with noncoherent multiple frequency shift-keyed (MFSK) modulation and Viterbi maximum likelihood decoding on a Rician fading channel is examined in detail. While the primary motivation underlying this work has been concerned with system performance on the planetary entry channel, it is expected that the results are of considerably wider interest. Particular attention is given to modeling the channel in terms of a few meaningful parameters which can be correlated closely with the results of theoretical propagation studies. Fairly general upper bounds on bit error probability performance in the presence of fading are derived and compared with simulation results using both unquantized and quantized receiver outputs. The effects of receiver quantization and channel memory are investigated and it is concluded that the coded noncoherent MFSK system offers an attractive alternative to coherent BPSK in providing reliable low data rate communications in fading channels typical of planetary entry missions.
    • Phase-Coherent Dual-Frequency Link for High-Precision Doppler Tracking on the Apollo-Soyuz Mission

      Berg, A. C.; Stiffler, J. J.; Young, D. G.; Raytheon Co. (International Foundation for Telemetering, 1975-10)
      During the Apollo-Soyuz Test Project, a phase-coherent dual-frequency VHF link was scheduled to be established between the Docking Module and the Apollo Command Service Module. The purpose of the radio link was to enable measurements of the relative Doppler between the two modules to an accuracy of the order of one milliHertz. These measurements will be used to detect mass concentrations in the earth's crust of the order of 10 milligal and greater. The transmitter has a high stability master oscillator common to both channels. The receiver has a local oscillator with identical stability characteristics; its two channels employ phase-lock loops. The receiver is followed by a Doppler processor and tape recorder to extract and encode the desired gravity field information. This paper describes the instrumentation system concept and its implementation. It also contains an error budget for the deterioration of the Doppler accuracy due to various instrumental and propagation effects.
    • Multimission Spacecraft Dataplexer

      Cosme, Rafael; Lokerson, Donald; NASA, Goddard Space Flight Center (International Foundation for Telemetering, 1975-10)
      A low power, small size, building block type of central data system has been designed for use in a number of explorer type missions. The Data Multiplexing Unit was designed to satisfy a wide range of requirements among the several spacecraft. The resulting design includes preprogrammed Read Only Memories (ROM's) to generate the telemetry format tailored to the particular mission requirements. The relatively small size and low weight and power dissipation attained was largely due to the use of PMOS technology. The addition of sub-commutators in groups adequate to meet the particular spacecraft requirements allows low data rate experiments to be time multiplexed into a single main input channel for a more efficient data collection and processing operation.
    • Data Collection Using Adaptive Phased Array

      Noji, T. T.; AIL (International Foundation for Telemetering, 1975-10)
      Adaptive Ground Implemented Phased Array or AGIPA provides a rapid and cost effective means to read out and interrogate a very large number of earth based sensors. AGIPA locates an array in space but locates all of its beam forming and beam steering network on the ground; thereby providing multiple high gain beams to be formed with minimal complexity in space. AGIPA offers: * Less total system cost by placing a high gain array on a central data collection system and reducing the cost of each of the thousands of sensors. * Rapid data collection due to electronic beam steering as well as through formation of multiple beams. * Nulling of unintentional RFI that can disable the entire data collection system.
    • Session Opening Comment: The Broad Economic Importance of Service Applications

      Hupe, Howard H.; Department of Health, Education, and Welfare (International Foundation for Telemetering, 1975-10)
    • Standardization: Aid to Innovation

      Byers, Robert A.; Jet Lab. Of the Cal. Tech. (International Foundation for Telemetering, 1975-10)
    • COMSAT General Ranging Equipment Development

      Onufry, Michael; Jankowski, Joseph A.; COMSAT Laboratories (International Foundation for Telemetering, 1975-10)
      The range to the spacecraft is an important parameter for determining the transfer and synchronous orbits. The ranging equipment developed for the COMSAT General TT&C earth stations uses a fixed-tone technique to determine the distance from the earth station antenna to the satellites. Specifically, the range is calculated from the round trip propagation delay, which is determined by measuring the phase shift in four coherent audio tones. This system is similar to the ranging equipment used at the INTELSAT earth stations. New integrated circuit (IC) technology has permitted individual tone transmission which was previously not available. The ranging tones are frequency modulated in both the up- and down-links in the INTELSAT system. However, in the COMSAT General system the tones are frequency modulated in the up-link and phase modulated in the down-link. Hence, new techniques are required to determine the phase shift of the earth station equipment.